Sulfurized Polyacrylonitrile Cathodes With Rapid Redox Kinetics for High-Capacity and Long-Cycle-Life Lithium-Sulfur Batteries.

The quasi-solid-state reaction process in sulfurized polyacrylonitrile (SPAN) has emerged as a promising strategy to mitigate the polysulfide shuttle effect in lithium-sulfur (Li-S) batteries. However, the practical implementation of SPAN cathodes in ether-based electrolytes remains challenging due to solvation-induced structural rearrangement stemming from sluggish redox kinetics. Herein, a hierarchically structured composite (denoted as HSPAN) is developed through pyrolytic transformation of polystyrene (PS) templates coupled with carbon nanotubes (CNTs) network integration. This engineered architecture establishes dual electron-ion transport channels, which synergistically enhance sulfur redox kinetics, suppress short-chain sulfur dissolution, and enable stable charge/discharge cycling in ether electrolytes. The optimized HSPAN cathode delivers a specific discharge capacity of 1145 mAh g⁻¹ at 1 C rate with a sulfur content of 50%, maintaining 82% capacity retention over 800 cycles. Density functional theory (DFT) calculations reveal that the sulfurization treatment significantly narrows the HOMO-LUMO energy gap by modulating the electronic structure of polyacrylonitrile, thereby enhancing the conductivity and redox activity of the material, providing a theoretical basis for designing high-performance lithium-sulfur battery cathodes. This work provides fundamental insights into the solvation dynamics of sulfurized polymers and demonstrates a viable pathway toward practical high-energy-density Li-S batteries through rational electrode engineering.